Uncle Vernon ripped open the bill, snorted in disgust, and flipped over the postcard . " Marge's ill, " he informed Aunt Petunia. " Ate a funny whelk. --."
If you're studying for a chemistry exam, one card can ask you what the chemical symbol for Neon is, and if you flip it over, it can also make sure you know what Ne represents.
如果你正在准备化学考试,一张卡片可以考查你氖的化学符号是什么,它转过来,它也可以确保你知道 Ne 代表的是什么。